Pity that control theory is not taught in grade school. It explains so much from economics to climate. It doesn't have to get as deep as designing a PID loop. Or Laplace Transformations. Just a few general principles.
You are right. There are a lot of other things that would be wonderful if they taught them in grade school. Basic economics for example.
OK - this thread gives me insight into what happenned in the Easter isalands. And of course I am not saying it can't happen now as well!
There are three arguments that I wish to address (and bar gratutitous insults I think they cover the points raised by other posters in response to my moderate statements earlier).
1. GW is not happenning. Either it never happenned, or it can't happen because the science is clear and says it can't, or data from the last few years (of cooling) means that it is not happenning.
I don't think we can easily reach agreement on these matters. Anyone who makes simple statements (inclusing me) will be missing out a lot of the necessary detail. The reality is the subject of 1000s of scientific papers saying different and sometimes contradictory things. It is easy to cherry-pick these to support any view - especially of selective quotes, out of context, are taken.
When I found myself when wanting uptodate answers the only way (from internet blogs + skimming some of teh literature) was to read blog posts and then carefully follow the debate afterwards. That is several 100 posts of debate, most of which are substantive and well referenced. If you can't find such discussion you will not have a realistic view. If you don't have time to do it you should admit it. If you can't find such discussion, with all shades of opinion represented and real discussion of facts rather than polemic, try first Realclimate and also the (many) pro and anti AGW sites referenced from it.
Whatever your read on the web will have a polemic element, but you can find proper discussion as well.
If you want a comprehensive perspective you need to conduct an impartial literature review, with several 1000 papers (probably 10,000 papers, I don't know). Short of this, you should check the IPCC documents. If you ignore the (political) summaries, and go to the working group reports you will find really useful information. these are people who have done their best to review and make sense of the literature - work out what are the uncertainties - structural & other - and reach conclusions.
Not as much fun as two-line blog comments. Of course the same applies to anything I write here so i don't expect I can help much. My reply (in two lines) is that the models are well cross-validated not just on recent climate data but in many other ways, so the figures (1.5 - 4 C per CO2 doubling) of sensitivity are fairly robust. They have not changed much as new research is added. They represent still a lot of uncertainty. And what the temperature is in a given decade depends on many other forcing factors - and you need to look carefully at the literature and models to see what it does or does not prove.
I realise the above will not convince many who read it - but as I say if it did i would think less well of them. This is a complex matter and simple arguments do not suffice.
2. the feedbacks must be negative, since we are here. They can't be positive, or there would be swings of 100s of degrees.
This results from a simplistic (sic) model of climate. It is not a linear system. It has many different factors which interact. You would therefore expect some negative feedbacks, some positive. You would expect feedbacks to work over relatively small ranges. (Some interactions will remain the same over large ranges, some will not). the correct conclusion from history is that their can be local minima resulting in stationary points but these are not necessarily stable with time, and certainly not stable with large perturbations. the same applies to arguments like "It is obvious - here is the dominant feedback!". Determining which feedbacks are dominant and why is complex, and not settled by two line blogs. Also probably not fixed with time.
3. regardless of the science governments are bad, and therefore no government action can be constructive.
This is a (defeatist) argument that I have a lot of sympathy with. Governments are not generally motivated to acheive long-term ends, especially in democracies where the pressure is to win an election this year or next, not to make a better world in 20 years. Still, public opinion counts, people are not always deceived all the time, and also democratic governments are sometimes controlled by people with genuine vision and the desire to have a long-term legacy. Even so, people may be wrong, but there is hope. And there is also hope, for different reasons, for Russia (barely democratic) and China (not democratic) to take action with a long-term perspective.
Anyway, I am proposing that governments cede control to a market system. It has been done before (financial deregulation, leaving the gold standard, etc). You may feel it can't happen now. But if intelligent (remember Simon's IQ > 140 comments) people start reflecting and responding with inquiry and wish to find the truth rather than gut reactions there is hope.
The European system is broken. It was broken when first envisaged. Any such sytem, internationally, will be subject to trade-offs between interest groups as each tries to grab as much money as possible from teh changes. That is not the point. The European system, now in place, can be revised, anomalies reduced and eventually given teeth. The main reason it is broken is that some countries allocated quotas unreasonably large - so it ha no effect. All this can be mended. It is a system that with time will allow real controls in a progressive least harmful way.
Just as a tax system it will never be perfect, but it is necessary. (A few here will say that taxes are never necessary, that intranational disputes can best be resolved by a purely anachist system which is self-funding. Fine - we can all dream. But look to the example of the Marxist dreamers before you imagine such an ideal is workable).
PS - I am the stupid one in my family and would not pass Simon's 160+ test for working on Polywell, though my sister would. On the other hand, having IQ once measured as quite high (I have never voluntarily taken IQ tests but this was school) I am clever enough to know that successful outcome in most matters requires curiosity, hard work, determination, and stickability - intelligence is a help, and speeds things up when well used. But more often it just helps us be stupid in a more devious way!
Last edited by tomclarke on Wed May 20, 2009 9:45 am, edited 1 time in total.
regardless of the science governments are bad, and therefore no government action can be constructive.
Governments are bad. However, there is something governments can do. They can fund research to lower the costs of the alternatives below the cost of current energy sources. However, that leads to less government control and less government income than the various taxes proposed.
It is estimated that the taxes required to get significant changes to behavior would need to triple or more energy prices (look at what the Euros have accomplished with a mere doubling of prices - CO2 is rising faster than in low tax USA). However, the energy taxes have accomplished one thing. Industry is leaving Europe.
I don't propose repeating that experiment in the USA.
Engineering is the art of making what you want from what you can get at a profit.
I like to look at complex phenomena as vectors and scalars.
The first thing you need to know about a component is it's Magnitude. The next thing you need to know is it's Direction.
If an effect is trivial, you don't care about the direction. If an effect is substantial, then the direction is very important.
3/4ths of the surface of the planet is water. Water vapor is the most significant global warming gas in the atmosphere (something like 20 times the effect of CO2)
The percentage of water vapor in the atmosphere increases with heat. We don't care if the effect is linear or not, the direction is the same.
If an increase in water vapor resulted in an increase in heat, the Vector would be towards Hot in a recursive loop.
This obviously does not happen, and therefore proves the Vector is in the opposite direction. -> Cold
The scalar is not trivial, it is or great magnitude compared to every other factor out there. There is no other scalar on the horizon of any significance compared to the Water vapor vector.
Everything else put together wouldn't approach an effect that equals even 10 % of the water vapor effect. For that reason, we don't care about their direction because their scale is insignificant.
Look at a spectral absorption chart. Luckily I have one here with me !
Water vapor not only absorbs a lot more heat than CO2, it's FAR more abundant.
Water vapor drives the system and all other effects are trivial.
The point is that water vapour depends on temperature but the water vapour content of the atmosphere equilibrates quickly (residency time a few days). Therefore the effect on temperature is a feedback not a forcing.
It is a positive feedback, as you would expect, because higher T => more water =>more greenhouse. This is not enough to make the system unstable to local perturbations, but does mean that any forcing will be amplified.
The relative magnitude of water vapour and CO2 GH effect can be calculated. CO2 is approximately 1/4 the magnitude of water.
Given the complexity of this system, and the fact that even for the effect you suppose (which does not take account of varying temp and H2O content at dfferent heights, or the warming/cooling effect of absorption at different heights, or ...) the quantitative factors are uncalculated, do you think a neutral observershould be convinced by this - or any other short blog, ratehr than a serious analysis which references the literature and attempts to quantify these issues - either empirically or theoretically?
I looked around a bit and found a nice overview of the effects of CO2 & water vapour with numbers, taking into account the different spectral absorbences and overlap etc.
Of course to be sure of this you need to look at the model source code, and then check whether you think the model used is adequate etc etc.
I am afraid I edited my post with the new message. Sorry! My old post is preserved in your reply anyway!
Best wishes,
Tom
Last edited by tomclarke on Wed May 20, 2009 8:44 pm, edited 1 time in total.
RavingDave wrote:
If an increase in water vapor resulted in an increase in heat, the Vector would be towards Hot in a recursive loop.
So to understand this you need some equations:
T = global tmp, at given initial CO2 & water vapour
fc = forcing from additional CO2
fw = (feedback) from additional water vapour
with coefficients Sc & Sw repectively.
So T' = T +Sc.fc +Sw.fw (T' = temp with forcing & feedback)
Also, the water vapour forcing depends on Temperature with coefficent Wt, the local derivative:
fw = (T'-T)Wt
putting these together:
T'-T = fw/Wt = Sc.fc+Sw.fw =>
fw = Wt.Sc.fc/(1-WtSw)
and total effect of CO2 forcing is therefore:
fcSc[1 + Wt.Sw/(1-WtSw)]
from this you can see that the amplification factor from the water positive feedback is finite as long as WtSw < 1. the recursive loop reaches a finite asymptote.
Your argument that positive feedback => instability is not true.
Simon, as someone who knows control, will understand this.
Best wishes, Tom
PS - I hope this clarification would sway your neutral (control theory unskilled) observer
What would give me pause to think, were I an AGW skeptic, is why so many people of good will and rational throught (such as ravingdave) can easily be quite convinced that their rule of thumb calculations, in subjects they have little experience, are likely to be more acurate than thousands of scientists who have been studying the subject for a long time.
The explanations for most of the common misunderstandings are out there on the web in an easily accessible form. But what is this prejudice that means they are not accepted? I may be suspicious of other scientists but at least before I contradict what seems to be their settled view with my own theory I study what they say to see whether it shoots down my ideas. (Alas it often does!).
There are more sophisticated issues with GW. If you reckon all the GCM scientists are collectively deluded or biassed it is not possible to be sure that their models are skilful, even though they claim this. Unfortunately this view, which essentially says that all (or nearly all) the experts in the world must be ignored, makes progress difficult. It is difficult for anyone to independently verify the all science behind even one of the current GCMs.
By the time you have done this you will become one of the GCM scientists and perhaps like them suffer from the collective delusion (or feel the need to be untruthful) and therefore not be trusted.
But ravingdave's comments show that for at least some people the issue is a prejudice in favour of a particular outcome which accepts uncritically any argument appearing to support it, and refuses to engage with any opposing argument.
Your argument assumes that GCMs claim to account for the various decadal forcings, oceans, solar, etc. They are developing, and the newer ones do this, the older ones did not. Not surprisingly, predictions from older models do not match where the unmodelled forcings are dominant.
They never claimed to do this.
However the basic fact of CO2 increase => global temp increase (other things being equal) remains. It is validated both theoretically and empirically
You, and many other AGW septics seem sold on the idea that just during the 50 year period when AGW starts to affect the global temperature significantly there is a coincidental radiative minimum from the sun which will have more effect than the AGW. (I know the issue about the sun is the effect of particles on upper atmosphere, and complex).
Most people, having looked at the figures carefully, reckon that Maunder, Dalton, etc minimum or no, the effect of this is relatively small. You can look at the latest papers if you like - they are contradictory - meaning we don't really know - but neither make the influence very large.
You think that GCMs are fitted to historic global temperature. They are not. the free parameters are cross-validated in various ways, but not by fitting global temp.
What would give me pause to think, were I an AGW skeptic, is why so many people of good will and rational throught (such as ravingdave) can easily be quite convinced that their rule of thumb calculations, in subjects they have little experience, are likely to be more acurate than thousands of scientists who have been studying the subject for a long time.
Tom,
Science is advanced when one guy or a thousand question the conventional wisdom. It happens over and over. AGW is not exempt. And some times the back of the envelope guys come up with serious objections.
And you know - the AGW hysterics have captured a generation or a generation and a half of scientists plus the Nobel Prize Committee. It is going to take a while to unwind. Maybe another generation and a half.
And like the USSR with its wonderful theories of how a few really smart guys can run an economy better than millions of not so smart guys making their own decisions, millions (maybe billions) will die. In fact for some of the more extreme proponents of AGW that is a feature not a bug.
Now which side would I want to be on: certain mass death from wrecking economies or maybe mass death from GW? Seems simple to me - avoid certain catastrophe, hope to be able to deal with what is only a possibility. In any case kick the can down the road where we will have better tools for dealing with possibilities.
I don't know how old you are Tom but I'm old enough to know that zero of the catastrophes predicted in my lifetime (64 years and counting) have happened. If you don't count the DDT scare which caused the Africans to totally stop DDT use killing millions (finally in the process of being reversed). Or the franken food scare which is currently killing millions in Africa.
Say what do enviros have against Africans? Is it some kind of racial thing?
Thank the Maker the Chinese and Indians are not listening.
Engineering is the art of making what you want from what you can get at a profit.
